1. Field of the Invention
This invention in general relates to the field of ultrasonic imaging, and more particularly concerns an improved ultrasonic imaging module that effectively eliminates the sliding friction and gouging of the surface of the object to be scanned, such as a patient's skin, and automatically dispenses the proper amount of acoustic coupling fluid as the module moves along the object to be scanned.
2. Description of the Prior Art
In recent years ultrasonic imaging has become important in many areas of medical diagnosis, as for example in obstetrics, cardiology, and in the detection of tumors. Generally, in the ultrasonic imaging process, an ultrasonic camera or, what we shall refer to herein as an ultrasonic imaging module, is placed against and/or moved over the surface of the patient's body, or other object the interior of which it is desired to image. U.S. Pat. No. 4,246,791 describes an example of such a module. Generally, in the trade the term "transducer" is ambiguously applied to the entire ultrasonic "camera" or imaging module, to the piezoelectric element in which electrical energy is transformed into vibrating energy, and also to various portions of the system depending on the viewpoint. For clarity, in this disclosure, we shall refer to the ultrasonic "camera" as an ultrasonic imaging module and shall use the term "transducer" to designate that portion of the camera that actually vibrates. The piezoelectric element in which energy is transformed from electrical to vibrational shall be referred to as the "transducer element." Of course, in some instances, the transducer and the transducer element may be one and the same.
In order to obtain a meaningful ultrasonic image it is necessary that the interface between the ultrasonic imaging dule and the patient be predictable, repeatable, and conductive to the transmission of the ultrasonic energy with minimal distortion. In practice, the presence of some form of coupling fluid between the ultrasonic transducer and the biological tissue of the patient is required to eliminate the existence of a film or gap of air between the transducer and the tissue. Even a thin film of air can be highly detrimental to the effective process of coupling generated ultrasonic energy from the transducer to the patient and, subsequently, coupling the reflected ultrasonic energy, or echoes, from the patient to the transducer. Generally, an acoustic coupling fluid such as Aquasonic Scan.TM. by Parker Labs, Orange, NJ 07050 is applied to the surface of the patient's body to provide the desired interface. In some applications water provides an adequate coupling agent. Even with the fluid applied to the surface of the patient's body, however, the skin tends to alternately gather, slip irregularly past the transducer, and create other instabilities in the module/patient interface, since it is necessary to press relatively hard on the module against the patient's skin in order to obtain an effective transfer of the ultrasonic energy. Further application of the acoustic coupling fluid is generally done by hand, which results in varying amounts of the fluid being applied and which is also messy and time-consuming. Therefore, it will be highly desirable to provide an ultrasonic imaging module that overcomes these problems.